I have decided to donate a kidney. I know that with organizations like Renewal you can choose to donate to someone specifically. I was wondering if it is mutar to browse potential recipients and see whose situation seems most dire - ie a parent with young children, or someone who is contributing greatly to society like a doctor or something. Even asking the question seems much more horrible than it did in my head, and gives me much pause. But is it considered a violation of ein dochin nefesh mipnei nefesh? Furthermore, if it is not, would there be an inyan to give to someone in your town because "irecha kodmin"? Thank you.
First of all, kudos to you for this amazing selfless act!
I believe אין דוחין נפש מפני נפש means you mustn't cause someone to die in order to save someone else from death.
In this situation, you are not causing anyone to die. On the contrary, you are doing a heroic selfless act in order to save a life. You are not obliged to donate a part of your body to save someone from death, yet you are bravely doing so! You should be able to choose who you would like to give this amazing gift of life to.
This is made more clear when you think of the fact that one is perfectly permitted to choose to donate a kidney to someone close to them even if there are others who need it more direly.
Good luck, and wishing you an easy and quick recovery from the operation!
P.S. There's a Jewish organisation for kidney donations called Matnat Chaim
The Mishnah in Horiyos (13a) sets out an order of priorities for different situations.
One of the situations presented, is regarding saving a person's life. Let's say, that I can save only ONE person in a group of people, whose lives are ALL in danger, which one should I choose to save?
Since a kidney donation is a life saving act, I suggest that the order of priorities spelled out there, are applicable here.
If this application of the Mishnah is correct, then not only is it permitted to browse through potential recipients to find the most deserving person, you might be obligated to do so, to find the person who Halacha dictates to be the most deserving.
As with all practical Halachic questions, contact your local Orthodox rabbi for a definitive ruling on your question.